1. Field of the Invention
This invention relates generally to noise reduction in communication networks. More specifically, this invention relates to simultaneously removing far-end cross talk and inter-symbol interference from signals transmitted over an N-dimensional communication network.
2. Description of the Related Art
Insatiable demand for bandwidth in LAN applications has motivated the evolution of high-speed 1000BASE-T Ethernet from its predecessors, such as Fast Ethernet 100BASE-T and 10BASE-T.
In order to achieve the high throughput of Gigabit Ethernet, impairments such as cable attenuation, echo, near-end cross talk (NEXT), and far-end cross talk (FEXT) over the cable channel(s) must be reduced as much as possible. Another source of errors in baseband communication systems is intersymbol interference (ISI) arising from the dispersive nature of the communications channel, i.e. pulse distortion arising from the non-ideal filtering characteristics of the transmission channel leading to interference between symbols.
Attenuation, echo, and NEXT can be controlled through the use of a linear equalizer, a decision feedback equalizer (DFE), echo cancelers, and NEXT cancelers. However, none of these conventional components removes FEXT noise.
It is nonetheless desirable to reduce errors introduced in transmitted signals from ISI and FEXT. Although the magnitude of FEXT noise is usually much smaller than NEXT interference, any reduction of FEXT can only improve the performance of a Gigabit Ethernet Transceiver, as well as other communication networks having similar impairments. It is also true that if FEXT and ISI is removed, then the resulting Gigabit Ethernet Transceiver may be usable with cable that is either longer or of inferior quality than specified by industry standards.